This Chicago-set family drama follows a policewoman who causes a rift with her three cop brothers when she decides to join the department's Internal Affairs division.
When Don's ex-partner Paul is investigated for the death of his wife, Abby and Lina look into how she really died, which may lead to Don's old cases being reopened.
Meanwhile, Lina worries if her partnership with Abby will change after the birth of her baby, and Abby's relationships with Danny and Brody heat up.